Recuperator burners are known. Such burners typically incorporate a recuperator sleeve of ceramic material or the like that is disposed in spaced-apart surrounding relation to an axial gaseous fuel supply tube leading to a burner head. Combustion air travels along the annulus between the fuel supply tube and the recuperator sleeve for combustion with the gaseous fuel at the burner head. A portion of the combustion product gases travels back over the exterior of the recuperator sleeve in counter-current flow to the combustion air. Due to the high temperature of the combustion product gases, the recuperator sleeve becomes heated. Accordingly, the combustion air traveling through the interior of the recuperator sleeve also increases in temperature. The increased temperature of the combustion air promotes improved combustion at the burner head.
It is desirable to improve the heat transfer across the recuperator sleeve. To provide such improved heat transfer, past recuperator sleeves have incorporated various contoured surface arrangements having arrangements of outwardly projecting hollow protrusions. While such prior contoured surface recuperator sleeves have been somewhat successful, they have relied generally on surface protrusions that form relatively wide angles with one another. That is, the protrusions of prior devices form surfaces that are at relatively shallow angles relative to the base surface of the sleeve.